Abstract
Mitochondria are the powerhouses of mammalian cells, which participate in series of metabolic processes and cellular events. Mitochondria have their own genomes, and it is generally acknowledged that human mitochondrial genome encodes 13 proteins, 2 rRNAs and 22 tRNAs. However, the complexity of mitochondria derived transcripts is just starting to be envisaged. Currently, there are at least 8 lncRNAs, some dsRNAs, various small RNAs, and hundreds of circRNAs known to be generated from mitochondrial genome. These non-coding RNAs either translocate into cytosol/nucleus or reside in mitochondria to play various biological functions. Here we present an overview of regulatory non-coding RNAs encoded by the mammalian mitochondria genome. For overall understandings of non-coding RNAs in mitochondrial function, a brief summarization of nuclear-encoded non-coding RNAs in mitochondria is also included. We discuss about roles of these non-coding RNAs in cellular physiology and the communication between mitochondria and the nucleus.
Highlights
Mitochondria are vital to cells and are involved in multiple essential cellular events
In this review we will focus on known regulatory noncoding RNAs encoded by the mitochondrial genome, and we present a summarization of nuclear-encoded non-coding RNAs found in mitochondria for overall understandings about ncRNAs in mitochondria-nucleus communication
Among all the small RNA reads from oocytes and zygotes of mice, about 20% of the reads were mapped to mitochondrial DNA, and 80–90% of the reads were classified as PIWI-interacting RNAs (piRNAs) based on the size; these piRNAs were encoded by both strands of the mouse mitochondrial genome, and were highly expressed from the loci corresponding to mitochondrial tRNAs, 16S rRNA, and D-loop region (Larriba et al, 2018)
Summary
Mitochondria are vital to cells and are involved in multiple essential cellular events. Recent years have witnessed the fast growing in understanding the great complexity of transcripts from the nuclear genome (Djebali et al, 2012; Iyer et al, 2015), and growing evidence has demonstrated the presence of mitochondria-encoded noncoding RNAs (ncRNAs) such as long non-coding RNA (lncRNA) (Jusic and Devaux, 2020), circular RNAs (circRNAs) (Liu et al, 2020; Wu et al, 2020; Zhao et al, 2020), small non-coding RNAs (sncRNAs) (Mercer et al, 2011; Jusic and Devaux, 2020), and double-stranded RNAs (dsRNAs) (Dhir et al, 2018) with potential regulatory functions, respectively (Figure 1).
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